U.S. patent application number 13/820748 was filed with the patent office on 2014-09-18 for shock attenuator for gun system.
This patent application is currently assigned to HALLIBURTON ENERGY SERVICES, INC.. The applicant listed for this patent is John H. Hales, Samuel Martinez. Invention is credited to John H. Hales, Samuel Martinez.
Application Number | 20140262271 13/820748 |
Document ID | / |
Family ID | 49783976 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140262271 |
Kind Code |
A1 |
Martinez; Samuel ; et
al. |
September 18, 2014 |
SHOCK ATTENUATOR FOR GUN SYSTEM
Abstract
A perforation gun string. The perforation gun string comprises a
perforation gun that forms at least part of the perforation gun
string; and a swellable material coupled to the perforation gun
string. The swellable material is configured to be exposed to a
downhole wellbore environment; the swellable material is configured
to swell in response to exposure to the downhole wellbore
environment; and the swellable material is configured to protrude
beyond an outer surface of the perforation gun string when it
swells.
Inventors: |
Martinez; Samuel; (Cedar
Hill, TX) ; Hales; John H.; (Frisco, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Martinez; Samuel
Hales; John H. |
Cedar Hill
Frisco |
TX
TX |
US
US |
|
|
Assignee: |
HALLIBURTON ENERGY SERVICES,
INC.
Houston
TX
|
Family ID: |
49783976 |
Appl. No.: |
13/820748 |
Filed: |
April 3, 2012 |
PCT Filed: |
April 3, 2012 |
PCT NO: |
PCT/US12/32004 |
371 Date: |
March 4, 2013 |
Current U.S.
Class: |
166/297 ; 166/55;
89/1.15 |
Current CPC
Class: |
E21B 29/02 20130101;
E21B 43/12 20130101; E21B 43/119 20130101; E21B 43/1195 20130101;
E21B 43/116 20130101 |
Class at
Publication: |
166/297 ;
89/1.15; 166/55 |
International
Class: |
E21B 29/02 20060101
E21B029/02 |
Claims
1. A perforation gun string for use in perforating a wellbore,
comprising: a perforation gun, wherein the perforation gun forms at
least a part of the perforation gun string; and a swellable
material coupled to the perforation gun string, wherein the
swellable material is configured to be exposed to a downhole
wellbore environment, wherein the swellable material is configured
to swell in response to exposure to the downhole wellbore
environment, and wherein the swellable material is configured to
protrude beyond an outer surface of the perforation gun string when
it swells.
2. The perforation gun string of claim 1, further comprising a
tandem coupled to the perforation gun, wherein the swellable
material is coupled to the tandem.
3. The perforation gun string of claim 1, wherein the swellable
material is coupled to the perforation gun.
4. The perforation gun string of claim 1, further comprising a
subassembly coupled to the perforation gun, wherein the swellable
material is coupled to the subassembly.
5. The perforation gun string of claim 1, wherein the swellable
material comprises one of low acrylic-nitrile, ethylene propylene
diene rubber, or a cross-linked polyacrylamide.
6. The perforation gun string of claim 1, wherein the swellable
material is coupled to perforation gun string in cavities of the
perforation gun string.
7. A downhole tool, comprising: a tandem for use in making up a
perforation gun; and a swellable material coupled to the tandem,
wherein the swellable material is configured to swell in response
to being exposed to a downhole wellbore environment and wherein the
swellable material is configured to permit fluid flow between an
annular region above the swellable material and an annular region
below the swellable material after the swellable material
swells.
8. The downhole tool of claim 7, wherein the tandem comprises a
surface cavity and the swellable material is retained within the
surface cavity.
9. The downhole tool of claim 7, wherein the swellable material is
divided into a plurality of separate pieces, each piece of
swellable material retained within a corresponding surface cavity
of the tandem.
10. The downhole tool of claim 7, wherein the swellable material is
configured to permit the fluid flow by being adapted in sections
having one or more longitudinal fluid channels disposed
therebetween.
11. The downhole tool of claim 7, wherein the swellable material
comprises particles, wherein the particles comprise one or more of
bead-shaped particles, sphere-shaped particles, ovoid particles, or
powder.
12. The downhole tool of claim 7, wherein the swellable material is
shaped to have one of a beveled edge and a ramp-shaped edge after
swelling.
13. The downhole tool of claim 7, wherein the swellable material is
layered.
14. The downhole tool of claim 13, wherein the swellable material
has an outer hard layer and an inner soft layer.
15. A method of perforating a wellbore, comprising: running a
perforation gun string into the wellbore to a perforation depth,
the perforation gun string comprising a swellable material coupled
to the perforation gun string; allowing the swellable material to
swell; and after swelling the swellable material, perforating the
wellbore.
16. The method of claim 15, wherein the swellable material is
coupled to a first tandem located above a perforation gun and
coupled to a second tandem located below the perforation gun.
17. The method of claim 16, wherein the swellable material allows
fluid flow between an annular region above the first tandem and a
region below the second tandem.
18. The method of claim 15, further comprising during the
perforating, the swellable material attenuating impact between the
perforation gun and a wall of the wellbore.
19. The method of claim 15, wherein the swellable material
comprises one of low acrylic-nitrile, ethylene propylene diene
rubber, or a cross-linked polyacrylamide.
20. The method of claim 15, wherein the swellable material is
molded to have a beveled edge after it swells.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a 371 National Stage of International
Application No. PCT/US2012/032004, entitled, "Shock Attenuator for
Gun System," by Samuel Martinez, et al., filed on Apr. 3, 2012,
which is incorporated herein by reference in its entirety for all
purposes.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
[0003] Not applicable.
BACKGROUND
[0004] Hydrocarbons may be produced from wellbores drilled from the
surface through a variety of producing and non-producing
formations. The wellbore may be drilled substantially vertically or
may be an offset well that is not vertical and has some amount of
horizontal displacement from the surface entry point. In some
cases, a multilateral well may be drilled comprising a plurality of
wellbores drilled off of a main wellbore, each of which may be
referred to as a lateral wellbore. Portions of lateral wellbores
may be substantially horizontal to the surface. In some provinces,
wellbores may be very deep, for example extending more than 10,000
feet from the surface.
[0005] A variety of servicing operations may be performed on a
wellbore after it has been initially drilled. A lateral junction
may be set in the wellbore at the intersection of two lateral
wellbores and/or at the intersection of a lateral wellbore with the
main wellbore. A casing string may be set and cemented in the
wellbore. A liner may be hung in the casing string. The casing
string may be perforated by firing a perforation gun. A packer may
be set and a formation proximate to the wellbore may be
hydraulically fractured. A plug may be set in the wellbore.
Typically it is undesirable for debris, fines, and other material
to accumulate in the wellbore. Fines may comprise more or less
granular particles that originate from the subterranean formations
drilled through or perforated. The debris may comprise material
broken off of drill bits, material cut off casing walls, pieces of
perforating guns, and other materials. A wellbore may be cleaned
out or swept to remove fines and/or debris that have entered the
wellbore. Those skilled in the art may readily identify additional
wellbore servicing operations. In many servicing operations, a
downhole tool is conveyed into the wellbore and then is activated
by a triggering event to accomplish the needed wellbore servicing
operation.
SUMMARY
[0006] In an embodiment, a perforation gun string is disclosed. The
perforation gun string comprises a perforation gun that forms at
least part of the perforation gun string; and a swellable material
coupled to the perforation gun string. The swellable material is
configured to be exposed to a downhole wellbore environment; the
swellable material is configured to swell in response to exposure
to the downhole wellbore environment; and the swellable material is
configured to protrude beyond an outer surface of the perforation
gun string when it swells
[0007] In an embodiment, a downhole tool is disclosed. The downhole
tool comprises a tandem for use in making up a perforation gun and
swellable material coupled to the tandem. The swellable material is
configured to swell in response to being exposed to a downhole
wellbore environment and configured to permit fluid flow between an
annular region above the swellable material and an annular region
below the swellable material after the swellable material
swells.
[0008] In an embodiment, a method of perforating a wellbore is
disclosed. The method comprises running a perforation gun string
into the wellbore to a perforation depth, the perforation gun
string comprising a swellable material coupled to the perforation
gun string, allowing the swellable material to swell, and, after
swelling the swellable material, perforating the wellbore.
[0009] These and other features will be more clearly understood
from the following detailed description taken in conjunction with
the accompanying drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] For a more complete understanding of the present disclosure,
reference is now made to the following brief description, taken in
connection with the accompanying drawings and detailed description,
wherein like reference numerals represent like parts.
[0011] FIG. 1 is an illustration of a wellbore, a conveyance, and a
perforation gun string according to an embodiment of the
disclosure.
[0012] FIG. 2A is an illustration of a first perforation gun string
according to an embodiment of the disclosure.
[0013] FIG. 2B is an illustration of a tandem of a perforation gun
in a first state according to an embodiment of the disclosure.
[0014] FIG. 2C is an illustration of a tandem of a perforation gun
in a second state according to an embodiment of the disclosure.
[0015] FIG. 2D is an illustration of a tandem of a perforation gun
in the second state within a casing according to an embodiment of
the disclosure.
[0016] FIG. 3A is an illustration of a perforation gun string
according to an embodiment of the disclosure.
[0017] FIG. 3B is an illustration of a perforation gun string
according to an embodiment of the disclosure.
[0018] FIG. 3C is an illustration of a perforation gun string
according to an embodiment of the disclosure.
[0019] FIG. 3D is an illustration of a perforation gun string
according to an embodiment of the disclosure.
[0020] FIG. 4 is a flow chart of a method according to an
embodiment of the disclosure.
DETAILED DESCRIPTION
[0021] It should be understood at the outset that although
illustrative implementations of one or more embodiments are
illustrated below, the disclosed systems and methods may be
implemented using any number of techniques, whether currently known
or in existence. The disclosure should in no way be limited to the
illustrative implementations, drawings, and techniques illustrated
below, but may be modified within the scope of the appended claims
along with their full scope of equivalents.
[0022] Unless otherwise specified, any use of any form of the terms
"connect," "engage," "couple," "attach," or any other term
describing an interaction between elements is not meant to limit
the interaction to direct interaction between the elements and may
also include indirect interaction between the elements described.
In the following discussion and in the claims, the terms
"including" and "comprising" are used in an open-ended fashion, and
thus should be interpreted to mean "including, but not limited to .
. . ". Reference to up or down will be made for purposes of
description with "up," "upper," "upward," or "upstream" meaning
toward the surface of the wellbore and with "down," "lower,"
"downward," or "downstream" meaning toward the terminal end of the
well, regardless of the wellbore orientation. The term "zone" or
"pay zone" as used herein refers to separate parts of the wellbore
designated for treatment or production and may refer to an entire
hydrocarbon formation or separate portions of a single formation,
such as horizontally and/or vertically spaced portions of the same
formation. The various characteristics mentioned above, as well as
other features and characteristics described in more detail below,
will be readily apparent to those skilled in the art with the aid
of this disclosure upon reading the following detailed description
of the embodiments, and by referring to the accompanying
drawings.
[0023] Perforation guns are employed to perforate metal casing
strings and/or to improve the flow of hydrocarbons from
subterranean formations. Perforation guns may include a plurality
of explosive charges that explode with high energy. This sudden
release of explosive energy may undesirably move the perforation
gun, a perforation gun string, and/or a tool string in the
wellbore, possibly causing damage. For example, a lower portion of
the perforation gun string may be slammed into the casing, and a
piece of the perforation gun string may break off and fall into the
wellbore. Alternatively, other undesirable damage may be caused to
the perforation gun string and/or the tool string.
[0024] The present disclosure teaches providing shock attenuators
or shock absorbers coupled to an outside of the perforation gun
string to absorb and attenuate shock impacts of the perforation gun
string banging into a wall of the wellbore and/or the casing. The
shock attenuators may also contribute to maintaining the
perforation gun string in a properly aligned position within the
wellbore and/or casing, for example centrally disposed rather than
laying on the side of the casing in a horizontal or diverted
wellbore. The shock attenuation may be provided by swellable
material that is coupled into cavities in the surface of the
perforation gun string, for example in cavities and/or recesses
machined in the surface of tandems. When the perforation gun string
is run-in to the wellbore, the swellable material has not swelled
or has not swelled to a significant extent, and hence the swellable
material may not interfere with running the perforation gun string
into the wellbore. When the perforation gun string has been run in
to the depth at which the perforation will take place, the
perforation gun string may be held in position for an interval of
time suitable to allow the swellable material to swell
sufficiently, for example in response to the presence of fluids
that cause the swellable material to swell. The wellbore is then
perforated, and the swollen material attenuates and/or absorbs
impacts of the perforation gun string into the wellbore and/or into
the casing.
[0025] Turning now to FIG. 1, a wellbore servicing system 10 is
described. The system 10 comprises a servicing rig 16 that extends
over and around a wellbore 12 that penetrates a subterranean
formation 14 for the purpose of recovering hydrocarbons, storing
hydrocarbons, disposing of carbon dioxide, or the like. The
wellbore 12 may be drilled into the subterranean formation 14 using
any suitable drilling technique. While shown as extending
vertically from the surface in FIG. 1, in some embodiments the
wellbore 12 may be deviated, horizontal, and/or curved over at
least some portions of the wellbore 12. The wellbore 12 may be
cased, open hole, contain tubing, and may generally comprise a hole
in the ground having a variety of shapes and/or geometries as is
known to those of skill in the art.
[0026] The servicing rig 16 may be one of a drilling rig, a
completion rig, a workover rig, a servicing rig, or other mast
structure that supports a workstring 18 in the wellbore 12. In
other embodiments a different structure may support the workstring
18, for example an injector head of a coiled tubing rigup. In an
embodiment, the servicing rig 16 may comprise a derrick with a rig
floor through which the workstring 18 extends downward from the
servicing rig 16 into the wellbore 12. In some embodiments, such as
in an off-shore location, the servicing rig 16 may be supported by
piers extending downwards to a seabed. Alternatively, in some
embodiments, the servicing rig 16 may be supported by columns
sitting on hulls and/or pontoons that are ballasted below the water
surface, which may be referred to as a semi-submersible platform or
rig. In an off-shore location, a casing may extend from the
servicing rig 16 to exclude sea water and contain drilling fluid
returns. It is understood that other mechanical mechanisms, not
shown, may control the run-in and withdrawal of the workstring 18
in the wellbore 12, for example a draw works coupled to a hoisting
apparatus, a slickline unit or a wireline unit including a winching
apparatus, another servicing vehicle, a coiled tubing unit, and/or
other apparatus.
[0027] In an embodiment, the workstring 18 may comprise a
conveyance 30, a perforation gun string 32, and other tools and/or
subassemblies (not shown) located above or below the perforation
gun string 32. The conveyance 30 may comprise any of a string of
jointed pipes, a slickline, a coiled tubing, a wireline, and other
conveyances for the perforation gun string 32. In an embodiment,
the perforation gun string 32 comprises one or more explosive
charges that may be triggered to explode, perforating a wall of the
wellbore 12 and forming perforations or tunnels out into the
formation 14. The perforating may promote recovering hydrocarbons
from the formation 14 for production at the surface, storing
hydrocarbons flowed into the formation 14, or disposing of carbon
dioxide in the formation 14, or the like. The perforation may
provide a pathway for gas injection.
[0028] Turning now to FIG. 2A, FIG. 2B, FIG. 2C, and FIG. 2D, a
first embodiment of the perforation gun string 32 comprises a first
perforation gun 50a. In an embodiment, the first perforation gun
50a comprises a first tandem 52a, a second tandem 52b, and a
perforation gun barrel 54 coupled between the tandems 52. The
tandems 52 each comprise a plurality of shock attenuator material
56. The perforation gun barrel 54 comprises one or more explosive
charges 58 that may be fired to perforate the subterranean
formation 14 and/or a casing in the wellbore 12. The perforation
gun barrel 54 may comprise a tool body housing a plurality of
explosive charges 58. The explosive charges 58 may be retained by a
charge carrier structure (not shown) within the tool body. The tool
body may have scallops in its outer surface that may be proximate
to the explosive charges 58. The scallops may be areas where the
tool body is thinner and/or where the tool body defines a shallow
concavity.
[0029] Tandems are known to those skilled in the art. In an
embodiment, a tandem may be a short section of pipe or a
subassembly that is substantially solid metal with the exception of
having a relatively small diameter channel running from end to end
for containing detonation cord and/or for containing electrical
conductors. A tandem may have an indentation or groove that
promotes engaging and supporting the tandem, and hence supporting
the perforation gun to which the tandem is coupled, for example
engaging the tandem with elevators coupled to a travelling block of
a drilling rig.
[0030] As best seen in FIG. 2B, during run-in of the perforation
gun string 32, the shock attenuator material 56 is substantially
retracted and/or flush with an outside radial surface of the
tandems 52. As best seen in FIG. 2C, when the perforation gun
string 32 has been run-in to the position where the wellbore
subterranean formation 14 and/or casing is to be perforated, the
shock attenuator material 56 is deployed to protrude beyond the
outside radial surface of the tandems 52. As best seen in FIG. 2D,
after firing the perforation gun 50, the perforation gun string 32
may move within the wellbore 12, and the shock attenuator material
56 may contact a casing wall 59 first, before the perforation gun
string 32 contacts or bumps into the wellbore 12. Thus, the shock
attenuator material 56 may attenuate the impact that might
otherwise be delivered to the perforation gun string 32. In an
embodiment, the shock attenuator material 56 is placed such that
fluid flow in the wellbore 12 is not impeded, for example fluid
flow up and down the annulus defined by the wellbore 12 and the
outside of the perforation gun string 32, past the tandems 52a,
52b, is not blocked substantially by the shock attenuator material
56. In an embodiment, the shock attenuator material 56 may be
configured to leave a gap for fluid flow between an outer surface
of the shock attenuator material 56 and the wellbore 12 and/or the
shock attenuator material 56 may be configured to provide for one
or more longitudinal fluid channels or gaps between adjacent
sections of the shock attenuator material 56 to allow for fluid
flow therebetween.
[0031] While the shock attenuator material 56 is illustrated in
FIG. 2A as being rectangular in shape, it is understood that the
shock attenuator material 56 may be implemented in any shape, for
example in a circular shape, a square shape, a rectangular shape,
an oval shape, a star shape, a longitudinal strip shape, and/or a
circumferential ring shape (though the circumferential ring shape
may have passageways therethrough). In an embodiment, the shock
attenuator material 56 may be beveled or feature ramped edges.
Beveled and/or ramped edges may reduce the opportunity for the
shock attenuator material 56 to hang in the wellbore 12 and/or on
casing joints as the perforation gun string 32 is run into the
wellbore 12. Additionally, while shown arranged in a single row of
pads of shock attenuator material 56, the pads of shock attenuator
material 56 may be arranged differently, for example in a plurality
of rows, with the pads in different rows offset from each other or
lined up with each other. The tandem 52 may be machined to create
cavities or recesses into which the shock attenuator material 56
may be positioned so that it is initially retracted or flush with
the surface of the tandem 52.
[0032] The shock attenuator material 56 may have grooves or ridges
molded or cut into its surface. The shock attenuator material 56
may be molded and/or cut to create a surface having a number of
isolated protuberances or high points. These surface features may
promote the abrasion and removal of the shock attenuator material
56 as the perforation gun string 32 is removed from the wellbore 12
after perforation has completed, thereby reducing the possibility
that the shock attenuator material 56 may cause the perforation gun
string 32 to get stuck in the wellbore 12. These surface features
may promote adjusting the amount of shock attenuation and/or
adjusting the shock attenuation on-set with reference to
displacement of the perforation gun string 32 in the wellbore
12.
[0033] In an embodiment, the shock attenuator material 56 may be
layered or laminated, for example having an outer layer and an
inner layer. In an embodiment, the outer layer may be relatively
hard while the inner layer may be relatively soft. The hard outer
layer may resist scuffing and/or abrasion as the perforation gun
string 32 is run into the wellbore 12. When the perforation gun
string 32 is pulled out of the wellbore 12, after the shock
attenuator material 56 has swollen, the outer harder layer may
readily peel off when contacting the wellbore 12 and/or casing,
thereby promoting the movement of the perforation gun string 32 out
of the wellbore 12. In an embodiment, the inner softer layer may be
selected to shear in response to a shear force on the shock
attenuator material 56, thereby providing for a specific shear
location.
[0034] While in FIG. 2A, both the tandems 52a, 52b are illustrated
as having shock attenuator material 56, in an alternative
embodiment only one of the two tandems 52a, 52b have shock
attenuator material 56. Alternatively, in an embodiment, the shock
attenuator material 56 may be coupled to the perforation gun barrel
54 at a top edge and/or a bottom edge of the perforation gun barrel
54, for example coupled in scallops in the surface of the
perforation gun barrel 54. When the shock attenuator material 56 is
coupled in scallops in the surface of the perforation gun barrel
54, explosive charges 58 may not be located proximate to those
scallops. Alternatively, the shock attenuator material 56 may be
located among the explosive charges 58 but preferably not blocking
the explosive charges 58.
[0035] In combination with the present disclosure, one skilled in
the art will readily be able to determine the amount of shock
attenuator material 56 to use in assembling the gun string 32. The
amount of shock attenuator material 56 may be determined based on
an analysis of the magnitude of the mechanical energy that is
expected to be released during a perforation event. For example, a
perforation gun expected to release a relatively greater amount of
mechanical energy may be assembled with relatively more shock
attenuator material 56; a perforation gun expected to release a
relatively lesser amount of mechanical energy may be assembled with
relatively less shock attenuator material 56. The amount of shock
attenuator material 56 to use may also be determined based on the
properties of the shock attenuator material 56, for example the
energy absorbing properties and/or the hardness of the shock
attenuator material 56.
[0036] Likewise, the location and/or positioning of the shock
attenuator material 56 in the gun string 32 may be determined based
on an analysis of the disposition or location of the mechanical
energy that is expected to be released during a perforation event.
The analysis may indicate appropriate intervals along the gun
string 32 to locate shock attenuator material 56, for example every
5 feet, every 10 feet, every 20 feet, or at some other
interval.
[0037] In an embodiment, the gun string 32, including the
incorporated shock attenuator material 56, may be modeled and a
perforation event simulated with a computer program to evaluate the
suitability of the amount and location of the shock attenuator
material 56. For example, a Shock Pro simulation program may be
employed to simulate the perforation event. In an embodiment,
sacrificial mechanical structures may be incorporated into the gun
string 32 to determine actual engagement of the gun string 32 with
the wellbore 12 as a result of an actual perforation event. For
example, a series of different length mechanical probes may be
deployed. If one of the mechanical probes contacts the wellbore 12
or casing, the probe may be broken off or deformed in some
distinguishable manner. Determining the shortest mechanical probe
that contacts the wellbore 12 may provide an indication of the
movement of the gun string 32 in the wellbore 12 resulting from
firing the perforation gun 50 and may also provide an indication of
the effectiveness of the shock attenuator material 56. This
information could be incorporated back into the perforation event
simulation tool to improve future perforation event simulations and
gun string designs.
[0038] In an embodiment, the shock attenuator material 56 may
comprise a swellable material and/or a combination of swellable
materials, for example a swellable material that is not swollen and
is retracted below the outside surface of the tandem 52 upon the
initiation of run-in and that remains substantially retracted until
the perforation gun string 32 is run-in to the perforation
location. Alternatively, the shock attenuator material 56 may
comprise a combination of swellable material and non-swellable
material in which the swellable material may motivate the
deployment of the shock attenuator material 56, and the
non-swellable material may principally promote shock absorption.
The swellable material may then swell in response to downhole
environmental conditions, for example in response to a downhole
temperature, in response to contact with water in the downhole
environment, in response to contact with hydrocarbons in the
downhole environment, and/or in response to other downhole
environmental conditions. Alternatively, the shock attenuator
material 56 may be deployed mechanically, for example by actuation
of a spring.
[0039] In an embodiment, the shock attenuator material 56 may be
any of a variety of swellable materials that are activated and
swell in the presence of water and/or hydrocarbons. For example,
low acrylic-nitrile may be used which swells by as much as fifty
percent when contacted by xylene. For example, simple ethylene
propylene diene rubber (EDPM) compound may be used which swells
when contacted by hydrocarbons. For example, a swellable polymer,
such as cross-linked polyacrylamide may be used which swells when
contacted by water. In each of the above examples, the swellable
material swells by action of the shock attenuator material 56
absorbing and/or taking up liquids. In an embodiment, the swellable
material may be activated to swell by one or more of heat and/or
pressure.
[0040] It is to be understood that although a variety of materials
other than the swellable material of the present disclosure may
undergo a minor and/or insignificant change in volume upon contact
with a liquid or fluid, such minor changes in volume and such other
materials are not referred to herein by discussions referencing
swelling or expansion of the swellable material. Such minor and
insignificant changes in volume are usually no more than about 5%
of the original volume.
[0041] In an embodiment, the swellable material may comprise a
solid or semi-solid material or particle which undergoes a
reversible, or alternatively, an irreversible, volume change upon
exposure to a swelling agent (a resilient, volume changing
material). Nonlimiting examples of such resilient, volume changing
materials include natural rubber, elastomeric materials, styrofoam
beads, polymeric beads, or combinations thereof. Natural rubber
includes rubber and/or latex materials derived from a plant.
Elastomeric materials include thermoplastic polymers that have
expansion and contraction properties from heat variances. Other
examples of suitable elastomeric materials include
styrene-butadiene copolymers, neoprene, synthetic rubbers, vinyl
plastisol thermoplastics, or combinations thereof. Examples of
suitable synthetic rubbers include nitrile rubber, butyl rubber,
polysulfide rubber, EPDM rubber, silicone rubber, polyurethane
rubber, or combinations thereof. In some embodiments, the synthetic
rubber may comprise rubber particles from processed rubber tires
(e.g., car tires, truck tires, and the like). The rubber particles
may be of any suitable size for use in a wellbore fluid. An example
of a suitable elastomeric material is employed by Halliburton
Energy Services, Inc. in Duncan, Okla. in the Easywell wellbore
isolation system.
[0042] In an embodiment, the swelling agent may comprise an aqueous
fluid, alternatively, a substantially aqueous fluid, as will be
described herein in greater detail. In an embodiment, a
substantially aqueous fluid comprises less than about 50% of a
nonaqueous component, alternatively less than about 35%, 20%, 5%,
2% of a nonaqueous component. In an embodiment, the swelling agent
may further comprise an inorganic monovalent salt, multivalent
salt, or both. A non-limiting example of such a salt includes
sodium chloride. The salt or salts in the swelling agent may be
present in an amount ranging from greater than about 0% by weight
to a saturated salt solution. That is, the water may be fresh water
or salt water. In an embodiment, the swelling agent comprises
seawater.
[0043] In an alternative embodiment, the swelling agent comprises a
hydrocarbon. In an embodiment, the hydrocarbon may comprise a
portion of one or more non-hydrocarbon components, for example less
than about 50% of a non-hydrocarbon component, alternatively less
than about 35%, 20%, 5%, 2% of a non-hydrocarbon component.
Examples of such a hydrocarbon include crude-oil, diesel, natural
gas, and combinations thereof. Other such suitable hydrocarbons
will be known to one of skill in the art.
[0044] In an embodiment, the swellable material refers to a
material that is capable of absorbing water and swelling, i.e.,
increases in size as it absorbs the water. In an embodiment, the
swellable material forms a gel mass upon swelling that is effective
for shock attenuation. In some embodiments, the gel mass has a
relatively low permeability to fluids used to service a wellbore,
such as a drilling fluid, a fracturing fluid, a sealant composition
(e.g., cement), an acidizing fluid, an injectant, etc., thus
creating a barrier to the flow of such fluids. A gel refers to a
crosslinked polymer network swollen in a liquid. The crosslinker
may be part of the polymer and thus may not leach out of the gel.
Examples of suitable swelling agents include superabsorbers,
absorbent fibers, wood pulp, silicates, coagulating agents,
carboxymethyl cellulose, hydroxyethyl cellulose, synthetic
polymers, or combinations thereof.
[0045] The swellable material may comprise superabsorbers.
Superabsorbers are commonly used in absorbent products, such as
horticulture products, wipe and spill control agents, wire and
cable water-blocking agents, ice shipping packs, diapers, training
pants, feminine care products, and a multitude of industrial uses.
Superabsorbers are swellable, crosslinked polymers that, by forming
a gel, have the ability to absorb and store many times their own
weight of aqueous liquids. Superabsorbers retain the liquid that
they absorb and typically do not release the absorbed liquid, even
under pressure. Examples of superabsorbers include sodium
acrylate-based polymers having three dimensional, network-like
molecular structures. The polymer chains are formed by the
reaction/joining of hundreds of thousands to millions of identical
units of acrylic acid monomers, which have been substantially
neutralized with sodium hydroxide (caustic soda). Crosslinking
chemicals tie the chains together to form a three-dimensional
network, which enable the superabsorbers to absorb water or
water-based solutions into the spaces in the molecular network and
thus form a gel that locks up the liquid. Additional examples of
suitable superabsorbers include crosslinked polyacrylamide;
crosslinked polyacrylate; crosslinked hydrolyzed polyacrylonitrile;
salts of carboxyalkyl starch, for example, salts of carboxymethyl
starch; salts of carboxyalkyl cellulose, for example, salts of
carboxymethyl cellulose; salts of any crosslinked carboxyalkyl
polysaccharide; crosslinked copolymers of acrylamide and acrylate
monomers; starch grafted with acrylonitrile and acrylate monomers;
crosslinked polymers of two or more of allylsulfonate,
2-acrylamido-2-methyl-1-propanesulfonic acid,
3-allyloxy-2-hydroxy-1-propane-sulfonic acid, acrylamide, and
acrylic acid monomers; or combinations thereof. In one embodiment,
the superabsorber absorbs not only many times its weight of water
but also increases in volume upon absorption of water many times
the volume of the dry material.
[0046] In an embodiment, the superabsorber is a dehydrated,
crystalline (e.g., solid) polymer. In other embodiments, the
crystalline polymer is a crosslinked polymer. In an alternative
embodiment, the superabsorber is a crosslinked polyacrylamide in
the form of a hard crystal. A suitable crosslinked polyacrylamide
is the DIAMOND SEAL polymer available from Baroid Drilling Fluids,
Inc., of Halliburton Energy Services, Inc. The DIAMOND SEAL polymer
used to identify several available superabsorbents are available in
grind sizes of 0.1 mm, 0.25 mm, 1 mm, 2 mm, 4 mm, and 14 mm. The
DIAMOND SEAL polymer possesses certain qualities that make it a
suitable superabsorber. For example, the DIAMOND SEAL polymer is
water-insoluble and is resistant to deterioration by carbon
dioxide, bacteria, and subterranean minerals. Further, the DIAMOND
SEAL polymer can withstand temperatures up to at least 250.degree.
F. without experiencing breakdown and thus may be used in the
majority of locations where oil reservoirs are found. An example of
a biodegradable starch backbone grafted with acrylonitrile and
acrylate is commercially available from Grain Processing
Corporation of Muscantine, Iowa as WATER LOCK.
[0047] As mentioned previously, the superabsorber absorbs water and
is thus physically attracted to water molecules. In the case where
the swellable material is a crystalline crosslinked polymer, the
polymer chain solvates and surrounds the water molecules during
water absorption. In effect, the polymer undergoes a change from
that of a dehydrated crystal to that of a hydrated gel as it
absorbs water. Once fully hydrated, the gel usually exhibits a high
resistance to the migration of water due to its polymer chain
entanglement and its relatively high viscosity. The gel can plug
permeable zones and flow pathways because it can withstand
substantial amounts of pressure without being dislodged or
extruded.
[0048] The superabsorber may have a particle size (i.e., diameter)
of greater than or equal to about 0.01 mm, alternatively greater
than or equal to about 0.25 mm, alternatively less than or equal to
about 14 mm, before it absorbs water (i.e., in its solid form). The
larger particle size of the superabsorber allows it to be placed in
permeable zones in the wellbore, which are typically greater than
about 1 mm in diameter. As the superabsorber undergoes hydration,
its physical size may increase by about 10 to about 800 times its
original volume. The resulting size of the superabsorber is thus of
sufficient size to flow and attenuate shock when the perforation
gun 50 is fired. It is to be understood that the amount and rate by
which the superabsorber increases in size may vary depending upon
temperature, grain size, and the ionic strength of the carrier
fluid. The temperature of a well typically increases from top to
bottom such that the rate of swelling increases as the
superabsorber passes downhole. The rate of swelling also increases
as the particle size of the superabsorber decreases and as the
ionic strength of the carrier fluid, as controlled by salts, such
as sodium chloride or calcium chloride, decreases and vice
versa.
[0049] The swell time of the superabsorber may be in a range of
from about one minute to about thirty-six hours, alternatively in a
range of from about three minutes to about twenty-four hours,
alternatively in a range of from about four minutes to about
sixteen hours, alternatively in a range of from about one hour to
about six hours.
[0050] In an embodiment, the shock attenuator material 56 embeds or
encapsulates bodies and/or particles of plastic, ceramic, glass,
metal, or other material. In this embodiment, the shock attenuator
material 56 comprises bodies and/or particles in addition to other
material, for example swellable material. In an embodiment, the
bodies and/or particles may have any form or shape. The bodies
and/or particles may be generally bead-shaped, sphere-shaped,
pyramid shaped, diamond shaped, ovoid-shaped, or shaped in some
other form. The bodies and/or particles may be one or more
geometrical shape with rounded and/or beveled edges and/or apexes.
The bodies and/or particles may comprise powder. The embedded
bodies and/or particles may promote reducing sliding friction
between the shock attenuator material 56 and other surfaces such as
a casing. The embedded bodies and/or particles may promote ease of
abrasion and break-up of the shock attenuator material 56 when the
perforation gun string 32 is removed from the wellbore 12. The
volume of embedded bodies and/or particles contained per unit
volume of the shock attenuator material 56 may be employed as a
design variable to adjust the amount of swelling that the shock
attenuator material 56 undergoes when exposed to swelling agents in
the wellbore 12.
[0051] Turning now to FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 3D,
several alternative embodiments of the perforation gun string 32
are described. As illustrated in FIG. 3A, the perforation gun
string 32 may comprise a second perforation gun 50b and a third
perforation gun 50c. Each of the perforation guns 50b, 50c are
substantially similar to the first perforation gun 50a, with the
exception that only one of the tandems in each perforation gun 50b,
50c comprises shock attenuation material 56. The second perforation
gun 50b comprises a third tandem 52c having shock attenuation
material, a perforation gun barrel 54, and a first standard tandem
60a, where the first standard tandem 60a does not feature shock
attenuation material. The third perforation gun 50c comprises a
fourth tandem 52d having shock attenuation material 56, a
perforation gun barrel 54, and a second standard tandem 60b, where
the second standard tandem 60b does not feature shock attenuation
material. The distance between the tandem 52c and the tandem 52d
may be deemed suitable for providing a desired amount of shock
attenuation.
[0052] As illustrated in FIG. 3B, the perforation gun string 32 may
comprise more than two perforation guns 50, where the top
perforation gun is configured like the second perforation gun 50b
and the bottom perforation gun is configured like the third
perforation gun 50c described with reference to FIG. 3A. One or
more perforation guns 50d may be coupled into the perforation gun
string 32 between the perforation guns 50b, 50c. For example, the
fourth perforation gun 50d may comprise standard tandems 60c and
60d that do not feature shock attenuation material. Again, the
distance between the tandem 52e and the tandem 52f may be deemed
suitable for providing a desired amount of shock attenuation.
[0053] As illustrated in FIG. 3C, the perforation gun string 32 may
comprise two perforation guns 50d-1, 50d-2, a first subassembly
70a, and a second subassembly 70b. The two perforation guns 50d-1,
50d-2 do not feature any shock attenuation material. Both the
subassemblies 70a, 70b feature shock attenuation material 56. As
with the description above, the shock attenuation material may be
provided in a variety of shapes and disposed in a variety of
locations around the radial surface or subsurface of the
subassemblies 70a, 70b. As illustrated in FIG. 3D, in an
embodiment, the perforation gun string 32 may comprise any number
of perforation guns 50d between the end subassemblies 70a, 70b. As
illustrated, in an embodiment, the perforation gun string 32 may
comprise a third perforation gun 50d-3, a fourth perforation gun
50d-4, a fifth perforation gun 50d-5, and a sixth perforation gun
50d-6. It is understood that the perforation gun string 32 may be
embodied with other numbers of perforation guns 50d coupled between
the end subassemblies 70a, 70b, including a single perforation gun
50d. In the embodiments described above, it is understood that
additional connectors, spacers, tools, and subassemblies could be
used between guns 50 and likewise could have shock attenuation
material 56 coupled to them.
[0054] Turning now to FIG. 4, a method 100 is described. At block
102, a perforation gun string is run into the wellbore, the
perforation gun string comprising a swellable material coupled to
the perforation gun string. For example, one of the perforation gun
strings 32 described above or another embodiment of the gun string
32 is run into the wellbore 12. At block 104, the swellable
material coupled to the perforation gun string is swelled. For
example, the shock attenuator material 56 swells over time in
response to downhole environmental conditions, such as contact with
water, contact with hydrocarbons, exposure to elevated temperature,
and/or other downhole environmental conditions. At block 106, after
the swellable material has swollen, the wellbore is perforated
using the perforation gun string, for example the explosive charges
58 are activated.
[0055] In an embodiment, after the perforation event, other
procedures may be performed, for example a flow test may be
performed. In an embodiment, after perforating the wellbore 12 the
gun string 32 may be left in the wellbore 12 to allow other
swellable material to swell, where the other swellable material
swells at a slower rate than the swellable material employed for
shock attenuation. The other swellable material may be used to seal
a zone of the wellbore 12 while performing some other procedure,
for example capturing a sample by a subassembly of the work string
18.
[0056] In an embodiment, the method 100 may further comprise
removing the shock attenuator material 56 from the perforation gun
string 32 and removing the perforation gun string 32 from the
wellbore 12. For example, the shock attenuator material 56 may
shear off from the perforation gun string 32 as the perforation gun
string is removed from the wellbore 12. In an embodiment, the shock
attenuator material 56 may be sheared off in response to engaging a
side of the wellbore 12 and/or a wellbore tubular wall and/or in
response to engaging a restriction in the wellbore 12. The shock
attenuator material 56 may abrade off of and/or slice (e.g., shear)
off of the perforation gun string 32. For example, upon
encountering a restriction, the shock attenuator material 56 may be
sheared due to the force applied by the smaller diameter component
at or near the diameter of the smaller diameter component. The
shock attenuator material 56 removed from the perforating gun
string 32 may fall to the bottom of the wellbore 12 where it may
remain or be removed in a subsequent retrieval operation.
Alternatively, the shock attenuator material 56 may, at least in
part, dissolve. When the shock attenuator material 56 is removed
from the perforating gun string 32, the pieces may be small enough
and/or light enough to be entrained with a produced fluid and
removed from the wellbore 12 without requiring a separate retrieval
operation.
[0057] In an embodiment, the perforation gun string 32 may be
modeled with a perforation gun firing simulation computer program
such as the ShockPro simulation program. This simulation may
promote a designer of the perforation gun string 32 to evaluate
different embodiments of the perforation gun string 32 and choose
an implementation and/or embodiment that is suitable to the subject
planned perforation job. Some of the parameters that may be taken
into consideration in selecting one implementation from a plurality
of alternative embodiments of the perforation gun string 32 may be
the number of explosive charges 58 in the gun barrel 54, the
location of the explosive charges 58 in the gun barrel 54, the
characteristics of the explosive charges 58 such as whether they
are "big hole" or "small hole" charges and the energy associated
with the charges, the number of perforation guns 50 in the
perforation gun string 32, and other design parameters. The
characteristics of the wellbore 12 may be taken into consideration
in selecting an embodiment of the perforation gun string 32, for
example, the presence of any narrow constrictions in the wellbore
12 may be taken into consideration.
[0058] While several embodiments have been provided in the present
disclosure, it should be understood that the disclosed systems and
methods may be embodied in many other specific forms without
departing from the spirit or scope of the present disclosure. The
present examples are to be considered as illustrative and not
restrictive, and the intention is not to be limited to the details
given herein. For example, the various elements or components may
be combined or integrated in another system or certain features may
be omitted or not implemented.
[0059] Also, techniques, systems, subsystems, and methods described
and illustrated in the various embodiments as discrete or separate
may be combined or integrated with other systems, modules,
techniques, or methods without departing from the scope of the
present disclosure. Other items shown or discussed as directly
coupled or communicating with each other may be indirectly coupled
or communicating through some interface, device, or intermediate
component, whether electrically, mechanically, or otherwise. Other
examples of changes, substitutions, and alterations are
ascertainable by one skilled in the art and could be made without
departing from the spirit and scope disclosed herein.
* * * * *